This invention belongs to the field of agriculture chemistry, and provides to the art new preemergence, postemergence, and aquatic herbicides, and methods for the use of the compounds for the control of weeds. Since the control of weeds is known to be a vital step in the maximization of crop yields, herbicides are now established as vital tools of the farmer and new and improved herbicidal compounds are in constant demand.
Despite the great amount of research which has been performed in the field of agricultural chemistry, active compounds closely related to the compounds of the present invention have not been previously discovered. The polyhalopyridones, which have two or more chlorine atoms as well as other alkyl and halo substituents on the pyridine ring, are known herbicides, but are obviously quite distinct from the present invention.
The organic chemical art has explored the pyridones rather extensively. For example, Ishibe et al., J. Am. Chem. Soc. 95, 3396-3397 (1973), disclosed a rearrangement of 3,5-diphenyl-1,2,6-trimethyl-4(1H)-pyridone. Such compounds, however, are not herbicides. Leonard et al., J. Am. Chem. Soc. 77, 1852-1855 (1955), taught the synthesis of 3,5-dibenzyl-1-methyl-4(1H)-pyridones, which compounds also have no herbicidal activity. The same principal author also disclosed 3,5-di(substituted-benzylidene)tetrahydro-4-pyridones, J. Am. Chem. Soc. 79, 156-160 (1957).
Light et al., J. Org. Chem. 25, 538-546 (1960), taught a number of 4-pyridone compounds including 2,6-diphenyl-1-methyl-4(1H)-pyridone, and related compounds bearing phenyl-ring substituents, none of which are herbicidally active.
An interesting recent article was published by El-Kholy et al. in J. Hetero. Chem. 10, 665-667 (published September 7, 1973). El-Kholy described a synthesis of 3,5-diphenyl-1-methyl-4(1H)-pyridone and related compounds by the reaction with methylamine of the sodium salt of 1,5-dihydroxy-2,4-diphenyl-1,4-pentadien-3-one.
A counterpart of the parent application Ser. No. 591,661, has been patented as Belgian Patent 832,702 (1976).
Articles reporting the herbicidal use of compounds of this invention include the following:
Berard and Rainey, Weed Sci. Soc. of Am. Abstracts 28, p. 13 (1977);
Waldrep and Taylor, J. Agric. Food Chem. 24, 1250-51 (1976);
Waldrep and Taylor, Weed Sci. Soc. of Am. Abstracts 266, p. 109 (1977);
Webster, Proc. Southern Weed Sci. Soc. 30, 103-12 (1977);
Wills, Proc. Southern Weed Sci. Soc. 30, 113-18 (1977).